This project seeks to assess the bone histology of pediatric patients maintained on chronic dialysis; to determine the value of newer, non-invasive markers or predictors of specific bone lesions; to determine whether maintaining some degree of hyperparathyroidism in these patients decreases the incidence of a dynamic bone disease; and assess the effect of recombinant osteogenic protein-1 in bone explants from bone biopsies to evaluate the possible role of this growth factor in bone formation and turnover in vitro.